1. Field of the Invention
The present invention relates to an apparatus for making a plate for offset printing, and particularly, to an electro-fax type of plate-making apparatus.
The offset printing generally needs an original plate, i.e., master paper, which has a size relatively larger than that of a normal document. Specifically, with the electro-fax type of plate-making apparatus, it is required to process the master paper and the manuscript which have the considerably larger sizes than those to be processed in a case of general copying. Therefore, the plate-making apparatus must be provided with an electro-fax processing system and an optical system, which are suitable in size for use with the master paper. Therefore, in order to avoid the necessity of enlarging the size of the apparatus, some known electro-fax types of plate-making apparatus have been designed as described below.
2. Description of the Prior Art
One known apparatus is provided at the top portion of the body thereof with a manuscript table made of a transparent plate glass, and is constructed so that a picture of the manuscript is reflected by a reflex mirror inclined to the manuscript table and is, in turn, projected by a projection lens onto a vertically disposed exposure table. However, this arrangement contains the following problems:
(a) When being set on the manuscript table, the manuscript must be placed face down on the table. This often causes much inconvenience to the operator and further causes much time to be expended for the setting of the manuscript; PA1 (b) The processing system for the master paper cannot be arranged in a straight line. This frequently causes the master paper to become jammed in the processing mechanism, and; PA1 (c) The reduction in size of the entire apparatus is naturally limited since the width of the processing system is determined according to the size of the master paper to be processed; PA1 (d) The operating of this apparatus is very complicated since the manuscript table is located at a distance from the operating panel, and; PA1 (e) The handling of this apparatus is also very complicated since the outlet for the master paper is located at a distance from the operating panel.
Accordingly, the expected reduction cannot be realized.
In order to solve these problems on the setting of the manuscript, another known apparatus is provided with an exposure window in its body opposite to the projection lens and with a getting-up and lying-down type of manuscript table which can cover said exposure window. However, this construction contains the following problems:
Further, the aforementioned problems (b) and (c) cannot be solved.
The processing system of the electro-fax type of plate-making apparatus generally comprises a wet developing device for developing the electrostatic latent image recorded in the master paper (i.e., photosensitive recording paper). A plurality of developing devices has been proposed, in which the developing liquid flows down onto a surface inclined to the horizontal direction so as to form a thin layer of developing liquid. The recording paper is forwarded on said thin layer of liquid and is thus processed to be developed. The Japanese Patent Publication No. 50(1975)-21857, for example, discloses a device wherein the developing is carried out with the recording paper being held on an electrically conductible base forming a support for the recording paper. However, this device is inferior in views of the handling process and of the operating rate when compared to a device wherein the developing is continuously carried out with the recording paper being forwarded. The Japanese Patent Public Disclosure No. 49(1974)-62148, discloses a device wherein the developing is carried out by injecting the developing liquid onto both surfaces of the recording paper. In this device, however, scratches on the face of the recording paper and unevenness of the developing are caused, since the trailing end of the recording paper is caused to flap by the jet of developing liquid after said trailing end of the paper has passed through the developing-liquid injection device.
The processing mechanism also comprises a device for drying and discharging the developed master paper (recording paper). A convenient drying and discharging device in the prior art is so constructed that the recording paper is forwarded by a pair of rollers along the guide plate, while being dried by hot wind produced by a blower and a heater, and is then discharged by a pair of paper discharging roller and paper suppressing roller. However, this device has a disadvantage in that, during a case wherein the drying of the paper is insufficent, the paper is soiled due to the transcription by the paper suppressing roller. If the paper suppressing roller causing the soiling of the paper is removed, the discharging of the paper becomes unstable since the trailing end of the paper is caused to flutter by the hot wind. Further, there is a suction type of device wherein, instead of said rollers and guide plate, a conveyor belt is used for carrying the paper with the latter being caused to adhere onto said belts by means of suction. However, the suction type of device has disadvantages due to its complicated construction and the high cost thereof.